Knife-sharpening mechanism for cutting machines



- 9 F. J; CLARK El AL 2918397 KNIFE-SHARPENING MECHANISM FOR CUTTING MACHINES Filed March 26, 1938 2 Sheets-Sheet 1 All" II 4 if f 75 i gfii l I v v v'\ N w I? VENTORS ATTO R N EYS Dec. 19, 193% F. J. CLARK El AL KNIFE-SHARPENING MECHANISM FOR CUTTING MACHINES Filed March 26, 1938 2 Sheets-Sheet 2 INVENTOR$ ATTORNEYS Patented Dec. 19 1939 KNIFE- SHARPENIN G MECHANISM FOR CUT- TING MACHINES chine Application March 26,

11 Claims.

This invention relates more particularly to improvements in knife-sharpening mechanisms for cutting machines of the portable type, commonly used for cutting cloth and other sheet materials,

and having an upright, vertically reciprocating knife which can be caused to follow a desired pattern or line of cut in a lay of cloth or other material by appropriately moving and guiding the machine about upon the supporting table for the material; and one purpose of my invention is to provide knife-sharpening means with drive mechanism of improved construction for such machines.

Other objects of the invention are to improve the drive mechanism for the sharpening means or elements of the sharpening mechanism of generally similar organization disclosed in application for United States Letters Patent, Serial No. 194,895 filed March 9, 1938, in the name of Frederick J. Clark; also to provide efiicient drive mechanism of exceedingly simple, strong and durable construction for the knife-sharpening means or elements of sharpening mechanisms for cutting machines of the type mentioned; and 25 also to provide knife-sharpening mechanism for cutting machines, having the other features of improvement and advantage hereinafter described and set forth in the claims.

In the accompanying drawings:

Fig. 1 is a side elevation of an upright reciproeating knife cutting machine, equippedwith knife-sharpening mechanism embodying our invention, a portion of shown in vertical section.

Fig. 2 is a fragmentary front elevation, partly in section thereof, and, like Fig. 1, showing the upper inoperative position of the grinding means.

Fig. 3 is a transverse, sectional elevation thereof on line 33, Fig. 1, and showing the grinding means lowered.

Fig. 4 is a sectional plan view of the sharpening means on line 44, Fig. 3.

Except with respect to the knife-sharpening mechanism and associated parts, this invention is 45 not concerned with the construction of the cutting machine, and it may be of the construction illustrated in the drawings or of other suitable construction. As herein disclosed, the machine comprises a base !5 adapted to rest and be moved about upon the table or supporting surface of the material to be cut, and an upright, slender standard It, which is rigid with and rises from the base and supports a stationary frame I? which houses an electric or other motor at I8 for driving the vertical knife l9. The knife .is resuch mechanism being FFlQE Company, Bu fialc, N; Y.

1938, Serial No. 198,298

(or. s1 '24s) ciprocated in a vertical guide slot in the front of the standard by the motor through drive connections comprising a slide to which the knife is secured at its upper end and which is reciprocated in a suitable guide on the frame by a pit- 5 man 2i connecting it to the crank pin of a crank wheel 22 secured to the front end of the horizontal'rotary shaft of the motor. 23 indicates the usual presser foot fixed to the lower endof a rod 2 t which extends Vertically in front of the 10' knife is, thus forming a guard for the knife, and is adjustable vertically, as in guides 25 and 25a on the front of the housing 33 to support the presser foot at different elevations suited to different lays of material to be cut. The rear end of the presser foot is shown as bifurcated and straddling the front edge portion of the standard to assist in preventing lateral deflection of the guard rod. The guard rod may be releasably held in different adjustments, as by a dog 26 carried byv the up-turned front end of a release lever 27 and pressed into holding engagement with the toothed side of the guard rod by a' spring 28. The lever 21 may be pivoted at one side of the machine in a position to be readily actuated for moving the dog to release the guard rod by a finger of the operators hand which grasps the hand1'e29 of the machine.

In the machine illustrated, the knife-grinding or sharpening means comprises flexible abrasive 30 band means preferably comprising flexible belts or strips 30 and 3| having grinding surfaces of carborundum or other suitable abrasive material and disposed at opposite sides of the knife in such a way that their abrasive surfaces can be caused to travel in sharpening contact with opposite sides of the front edge portion of the knife. These belts are power driven, for example, by the knife-operating motor of the machine, so that the runs or portions of the belts which contact with the knife, travel forwardly past the latter, and they are mounted-on a grinder carriage or support 32 arranged for movement up and down alongjor parallel with the knife edge to adapt the belts to sharpen the knife throughout its effective cutting length.

.Said' knife-grinding means or elements, together with the'drive means therefor, and other operative parts of the sharpening mechanism are preferably mounted on a frame part or housing 33 which is stationarily' but removably securedatthe front of the machine, asby screws 34" screwed into the front of the stationary frame ll: so that the sharpening mechanism may be applied to: and removed as an unit' from the machine. The housing 33 shown also serves as a cover for the crank wheel 22, pitman and other parts of the knife-operating mechanism.

The improved drive mechanism for the grinding means or elements is preferably constructed as follows:

Arranged vertically side by side in the housing 33 in front of the crank wheel are two parallel tubular shafts 35 and 36 which are journalled at their lower portions in suitable bearings 36a at the lower end of the housing 33. These shafts extend up through the upper end of the housing and through bearings 31 therefor in a gear casing 38 arranged above the housing 33 to move vertically toward and from the same on suitable guides, such as fixed posts 39, projecting up from the housing 33 through guide holes in the gear casing 38. J ournalled in the gear casing 38, preferably in suitable ball bearings 40, is a horizontal shaft 4| on the inner end of which is fixed a wheel 42 adapted to be driven by engagement with the crank wheel 22, which may be provided with a peripheral band or tire 42a of rubber or other suitable friction material to ensure effective driving of the wheel 42 by frictional contact therewith. The wheel 42 is adapted to be pressed into driving engagement with the crank wheel, as by coil springs 43 which surround the posts 39 between nuts at their upper ends and the top of the gear casing 38, and tend to move the gear casing downwardly to engage the Wheel 42 with the crank wheel 22.

The two shafts 35 and 35 are driven so as to rotate in opposite directions, preferably by intermeshing spiral pinions 45 and 43 fixed on the upper ends of the shafts 35 and 36 respectively, and one of which pinions, as 45, meshes with and is driven by a spiral pinion 41 on the horizontal shaft 4|. The pinions 45 and 4B are confined vertically in a chamber therefor in the gear casing 38, and since they are fixed to the tubular shafts 35 and 36, the latter are adapted to move vertically or endwise in their bearings with the gear casing 38 when the casing is moved for placing the wheel 42 into and out of driving engagement with the crank wheel 22.

Slidable lengthwise in the tubular shafts 35 and 3B, are two shafts 48 and 49 which are splined to the tubular shafts, as by keys 50 fixed in the tubular shafts and entering longitudinal keyways in the shafts 48 and 49, so that, while the latter shafts rotate with the tubular shafts, they are adapted to slide up and down therein. The shafts 48 and 49 extend downwardly out of or below the housing 33 with their lower ends extending through and journalled in bearing openings 5] in the grinder carriage 32. Drive pulleys 56 and 51 for the sharpening belts 30 and 3] respectively are fixed on the lower ends of the shafts 48 and 49 below the carriage 32, and relative vertical movement between said shafts and the carriage 32 is prevented by confining the carriage between the pulleys 56 and 51, and collars 58 fixed on the shafts and engaging the top of the carriage. The grinder carriage is thus adapted to move with the shafts 48 and 49 vertically or up and down along and parallel with the edge of the knife.

As shown, each belt 30, 3| passes around its drive pulley and an idler pulley 6i, and the two idler pulleys are journalled on slides 64 movable toward and from the drive pulleys on fixed legs 63 projecting rearwardly from the grinder carriage 32 and straddling the knife standard. The slides are yieldingly pressed rear-H wardly by springs 65 for maintaining the belts under suitable tension, and removal and renewal of the belts are readily effected by moving the idler pulley slides to slacken the belts.

The two sharpening belts in the construction shown are disposed at difierent levels, one above the other, and yieldingly pressed into sharpening contact with opposite sides of the edge portion of the knife by suitable means, such as the springpressed fingers 66, more fully shown and described in said copending application. These presser fingers are so shaped that their free end portions, which engage the belts, will hold those portions of the belts which contact the knife. at the requisite converging inclinations to insure grinding and maintaining longitudinal and bottom edges on the knife of wide, thin, bevelled form which are very sharp or keen and will remain sharp for the maximum time.

The parallel sliding shafts 48 and 49, which are guided vertically in the tubular shafts 35 and 36, act to guide the grinder carriage 32 to cause it to move up and down parallel with the knife edge, and prevent horizontal deflection or twisting of the carriage, thus providing desirable guide means therefor. In the illustrated embodiment of the invention, a guide block 87 on the carriage, see Fig. 4, slidably engages the rear edge of the standard 5. This block is movably retained in a tubular holder 68 having arms 69 secured to the carriage legs, and the notched front end of the block is held in yielding engagement with the rounded rear edge of the standard by a spring 70 in the holder back of the block. The parallel sliding shafts 48 and 49 supplemented by the block 6'1 yieldingly and slidingly engaging the standard, form a very efi'icient carriage guide.

The described drive mechanism drives the grinding means or belts rapidly and positively and, the belts while running, may be moved up and down along the edge of the knife for sharpening its longitudinal edge throughout its effective length and also sharpening its bottom end or point by any suitable means adapted to move the grinder carriage up and down. Preferably, the carriage is provided for this purpose, with a forwardly projecting, rigid finger piece 13 in the form of a ring adapted to be conveniently grasped between the thumb and finger for moving the carriage.

In the normal operation of the machine for cutting material, the grinder carriage with its grinding means or belts is held in its uppermost position, shown in Fig. 1, where it is out of the way and does not interfere with the cutting operation of the knife nor obstruct the view of the operator in using the machine, at which time it is necessary for him to be able to see the cutting edge of the knife so as to properly guide it to follow the pattern or required line of cut. The grinder carriage is releasably held in this upper, inoperative position and the drive wheel 42 held out of driving engagement with the crank wheel 22 to prevent driving the grinding means, preferably by a latch 15 in the form of a lever pivoted at 16 on the front of the grinder carriage. This latch has a laterally extending cam edge 18 which, when the grinder carriage has thelatch, acts on the stud to cam the grinder r carriage up to and releasably hold it in its uppermost inoperative. position.

The final. upward movement of the grinder carriage by the cam latch operates to disengage the wheel 42 from the crank wheel 22 and throw the drive mechanism for the grinding means out of action. When the sharpening mechanism is in use, thegrinder carriage is below its uppermost inoperative position, and the lower ends of the tubular shafts andili project downwardly out of the bottom ofthehousing in which position they are held by the downward pressure of the springs 23 on the gear casing 383. In camming the grinder carriage up to itsinoperative position by the latch l5, the carriage engages the projectirv lower ends of the shafts '35 and 3t and'lifts the shafts slightly, and through them lifts the gear casing 33 and moves the wheel 32 out of driving engagement with the crank wheel, thus stopping the grinding means.

When using the machine for cutting, the grinder carriage is retained in its raised, inoperative position by the latch '35, where. it is out of the way. In this position of the sharpener, the belts may be held outof contact with the knife to prevent cutting the belts or wearing the knife, by a wedge pin ll arranged to engage and spread apart the presser fingers 6. When the knife requires sharpening, .it is only necessary to release and lower the presser footto its lowest position, then release the latch and move the grinder carriage down and up along th reciprocating knife by means of the carriage finger piece '13. Only one or two down and movements of the grinding means is usually necessary, and at the end of the last up movement, the grinder carriage is latched in its inoperative position, as explained, and the machine is ready to continue its cutting.

In the described drive mechanism, the drive pulleys for the belts are secured directly on the lower ends of the two vertically movable shafts 8 and ts, and only a single train of three pinions is required between the releasable drive shaft ll and the belts for driving them. The vertically movable shafts are sturdily supported and guided for rotary and lengthwise movement and they, in turn, are directly journalled in the grinder carriage and afford simple and efficient means for guiding the carriage in its up and down movements along the knife and preventing horizontal shifting or twisting movements of thecarriage.

We claim as our invention:

. In a cutting inaci he, the combinetionwit a knife having a substantially up ight cutting edge and which is reoiprocated substantially in the lengthwise direc ion of its edge, of

grinding means comprising flexible abrasive e. means arranged to contact opposite sides of the edge portion of the knife, a supporting. for said grinding eans, drive mechanism for said grin ing means comprising two shafts ex te ding side by side above ca iage parallel with the knife edge, a power-operated driving motor geared to said shafts, a pair of shafts extending downwardly from and sliaable leng wise of and driven by said first two shafts, a pulley fixed directly on each of said slidable shafts and engaging said flexible band means for driving the same, and means fcr'incving said carriage with said grinding means and last men tioned shafts lengthwise along the knife edge.

2. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in .tated by and movable portion of each of said second engaging one of said belts.

the lengthwise direction of its edge, of knifeand grinding belts lengthwise along the knife edge, and drive mechanism for said belts comprising a pair of upright shafts arranged parallel with and at: opposite sides of the plane of the knife, a driving motor tions of saidshafts, a

geared to the uppenpor second pair of shaftsroe driving pulley fixed directly on the lowerend pair of shafts and 3. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in the lengthwise direction of its edge, of lznifegrinding belts disposed at opposite sides of the edge portion of the knife, asupporting carriage forsaid belts, and drive mechanism for said belts comprisinga pair of upright tubular shafts arranged at opposite sides of the'plane of the knife, a driving motor gearedto the upper ends ;of said shafts, shafts'slidable lengthwise in androtated by said tubular shafts with their lower ends journalled in said carriage, a belt-driving pulley fixed on the lower end of each of said last mentioned shafts and engaging one of said belts, and

means for moving said carriage and belts length wise along the knife edge. I

' 4. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in 10 with said carriage lengthwise of said first pair of shafts,and extending Q downwardly from said first shafts, and a belt.

the lengthwise direction of its edgaof knifegrinding elements disposed at opposite sides of the edge portion of theknife a supporting car riage for said elements, and drive mechanism for said elements comprising two shafts extending side by side above said carriage parallel withtheknife edge, a driving motor, releasable drive means from said motor to said shafts, a pair of shafts coaxial with rotated by said first mentioned shafts andarranged to move with said carriage lengthwise of the knife edge, drive connections between said last mentioned shafts and said grinding elements, and means. for moving said carriage lengthwise along the knife edge, said first mentioned shafts being shifted by movement of said carriage for actuating said re.- leasable drive means for stopping the grinding elements. v

5. In a cutting machine, the combination with ya knife having a substantially uprightcutting edge and which is reciprocated substantially in the lengthwise direction .of its edge, of knifegran ding elements disposed at opposite sides of the edge portion of the knife, a supporting carriage for said elements, and drive'mechanism for said elements comprising .twoshafts extending side by side above said carriage parallel with the knife edge, a driving motor, releasable drive means from said motor to said shafts, a pair of shafts coaxial with and rotatedjby said first mentioned shafts and arranged to move with said carriage'lengthwise of the knife edge, drive connections between the said last mentioned shafts and said grinding elements, means for moving said carriage lengthwise along the knife edge, and a latch for releasably retaining said carriage in an upper inoperative position, the movement of the carriage to the latched position actuating said releasable drive means through the medium of said first mentioned shafts for stopping the grinding elements.

6. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in the lengthwise direction of its edge, of knifegrinding elements disposed at opposite sides of the edge portion of the knife, a supporting carriage for said elements, and drive mechanism for said elements comprising two shafts extending side by side above said carriage parallel with the knife edge,'a driving motor, releasable drive means from said motor to said shafts, a spring tending to maintain driving relation between said releasable drive means and the motor, a pair of shafts coaxial with and rotated by said first mentioned shafts and arranged to move with said carriage lengthwise of the knife edge, drive connections between the said last mentioned shafts and said, grinding elements, means for moving said carriage lengthwise along the knife edge, a latch for releasably retaining the carriage in an upper inoperative position, the movement of the carriage to the latched position actuating said releasable drive means through the medium of said first mentioned shafts for stopping the grinding elements, and the unlatching of the carriage permitting movement of said releasable drive means by said spring for setting said drive mechanism in motion.

'7. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in the lengthwise direction of its edge, of knifegrinding elements disposed at opposite sides of the edge portion of the knife, a supporting carriage for said elements, and drive mechanism for said elements comprising two shafts extending side by side above said carriage parallel with the knife edge, a driving motor, releasable drive means from said motor to said shafts, a pair of shafts coaxial with and rotated by said first mentioned shafts and arranged to move with said carriage lengthwise of the knife edge, drive connections between the said last mentioned shafts and said grinding elements, said carriage being manually movable lengthwise along the knife edge, and a latch operable to releasably retain the carriage in an inoperative position and release said releasable drive means from the motor, said latch being arranged adjacent said carriage in position to be actuated by a finger of the hand which moves said carriage.

8. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in the lengthwise direction of its edge, of knifegrinding elements disposed at opposite sides of the edge portion of the knife, a supporting carriage for said elements, drive mechanism for said elements comprising two shafts extending side by side above said carriage parallel with the knife edge, a driving motor geared to said shafts, shafts movable lengthwise of and rotated by said first shafts and operatively connected to said grinding elements, means for moving said carriage and grinding elements lengthwise along the knife edge, a stationary upright guide, and a guide block movably' mounted on said carriage in rear of said upright guide and having a notched end held in yielding sliding engagement with the rear edge of said stationary guide and cooperating with said lengthwise movable shafts to guide said carriage in its movements along the knife edge.

9. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in the lengthwise direction of its edge, of knifegrinding elements arranged to contact opposite sides of the edge portion of the knife, a carriage supporting said elements, means for moving said carriage and grinding elements lengthwise along the knife edge, and drive mechanism for said elements comprising two shafts extending side by side above said carriage parallel with the knife edge, a driving motor, releasable drive means from said motor to said shafts, a pair of shafts rotated by said first two shafts and movable axially thereof with said carriage lengthwise of the knife edge, drive connections from each of said last-mentioned shafts to one of said grinding elements, latch means for moving said carriage to and releasably securing it in an upper inoper-v ative position, and means actuated by the operation of said latch means for actuating said releasable drive means to stop and start said grinding elements. 7

10. In a cutting machine, the combination with a knife which has a substantially upright cutting edge and is reciprocated substantially in the lengthwise direction of said edge, of knife-grinding flexible abrasive band means arranged to contact opposite sides of the edge portion of the knife, a supporting carriage for said band means, means for moving said carriage and band means lengthwise along the knife edge, a pair of shafts extending up from the carriage parallel with and at opposite sides of the knife edge and movable up and down with said carriage, supporting and driving pulleys for said band means one fixed directly on each of said shafts, a second pair of shafts each having a sliding drive engagement with one of said first pair of shafts, and a poweroperated motor and drive mechanism for rotating said second pair of shafts.

11. In a cutting machine, the combination with a knife which has a substantially upright cutting edge and is reciprocated substantially in the lengthwise direction of said edge, of flexible abrasive sharpening belts arranged to contact opposite sides of the edge portion of the knife, a supporting carriage for said belts, means for moving said carriage and belts lengthwise along the knife edge, a pair of shafts extending up from the carriage parallel with and at opposite sides of the knife edge and movable up and down with said carriage, supporting and driving pulleys for said belts each fixed directly on one of said shafts, a second pair of shafts each having a sliding drive engagement with one of said first pair of shafts, a power-operated motor, and a single gear train from said motor to said second pair of shafts for driving said sharpening belts.

FREDERICK J CLARK. CARL F. HILGEMAN. 

